Preparation of Functionalized p-Phenylenediamine Derivatives Using Arene−Iron Chemistry

Abstract

Selective displacement of chloride from cyclopentadienyl(1,4-dichlorobenzene)iron(1+) by a series of cyclic secondary amine nucleophiles is described. This selectivity, in combination with further manipulation of the complexes, allows access to a series of unsymmetrical and/or functionalized tetraalkyl-p-phenylenediamine complexes. A series of demetalated phenylenediamines were shown by CV to have redox potentials distributed over a range of 320 mV, as a consequence of remote functionality. Preliminary fluorescence studies on a series of electron acceptor-substituted phenylenediamines indicated quenching of the phenylenediamine fluorescence, attributable to rapid electron transfer.

Synthesis of (η6-arene)(η5-cyclopentadienyl) iron (II) complexes with heteroatom and carbonyl substituents Part II, Amino substituents

“…S N Ar reactions by oxygen nucleophiles can result in double displacements in dihalobenzene complexes [4]. For primary amines as nucleophiles, however, only mono-substitution is observed for 1,2-dichlorobenzene complexes [4], whereas disubstitution occurs for 1,4 analogues using piperazines as nucleophiles [5]. Recent work has shown that amino complexes can be synthesized using water as a solvent under mild conditions [6].…”

Photoinduced Synthesis of Dual‐Emissive Tetraphenylethene‐Based Dendrimers with Tunable Aggregates and Solution States Emissions

“…The synthetic route to the dendrimers is straightforward, exploiting the reactivity of η 6 ‐arene‐ η 5 ‐cyclopentadienyliron(II) toward a wide range of nucleophiles . For instance, to construct 0‐DEN‐TPE/DPP , η 6 ‐dichlorobenzene‐ η 5 ‐cyclopentadienyliron(II) was reacted with 4,4‐bis(4‐hydroxyphenyl)valeric acid via K 2 CO 3 ‐mediated nucleophilic aromatic substitution reaction (S N Ar), accessing the bimetallic building block (Scheme S2, Supporting Information).…”

Electrochemical One‐Electron Oxidation of Low‐Generation Polyamidoamine‐Type Dendrimers with a 1,4‐Phenylenediamine Core

“…The potentials given in Refs. 43 and 44 were recorded vs. the Fc/Fc + reference system and then converted to V vs. normal hydrogen electrode (NHE) by adding 0.400 V. The values given in the table above have been converted back to the V vs. Fc/Fc + scale by subtracting 0.400 V. [e] The original values are scaled to the Fc/Fc + reference system by subtracting 0.420 V.…”

“… Comparison of the data for the simple n ‐alkyl derivatives shows that oxidation becomes easier by 95 mV on passing from TMePD over TEtPD to TPrPD, and the decreasing effect with increasing chain length reflects the electron releasing effect of the alkyl chain. Isopropyl derivative T i PrPD is 80 mV more difficult to oxidize than the n ‐propyl derivative, which most likely reflects the steric effect of the isopropyl groups on the C Ar (2)‐C Ar (1)‐N‐R dihedral angle, which when different from zero results in reduced interactions between the N lone pair and the π system of the aromatic ring. The compound BPyrB containing a five‐membered ring system is 134 mV easier to oxidize than six‐membered analogue BPipB. This rather big difference was proposed43, 44 to reflect the difficulty in attaining a planar arrangement around the N atom in the radical cation of six‐membered piperidine derivative BPipB. Comparison of the data for the series of compounds having a conformationally restricted six‐membered ring substituent demonstrates a considerable effect of substitution in the remote C(2) position. The difference between the extreme values obtained for BPipB and BMorphB amounts to as much as 151 mV. …”